Method and apparatus for treatment of an animal processing wastewater stream

ABSTRACT

The present invention relates to the treatment of a wastewater stream that is generated from animal processing such as the processing of chicken, beef or pork. More particularly, the present invention relates to the separation of usable protein from an animal processing wastewater stream using a density modifier and a modification of the protein phase density to enhance lipid fat phase separation from protein solids.

CROSS-REFERENCE TO RELATED APPLICATIONS

-   -   This is a nonprovisional patent application of U.S. Provisional        Patent Application Ser. No. 62/872,162, filed 9 Jul. 2019, which        is hereby incorporated herein by reference.

Priority of U.S. Provisional Patent Application Ser. No. 62/872,162,filed 9 Jul. 2019, incorporated herein by reference, is hereby claimed.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

REFERENCE TO A “MICROFICHE APPENDIX”

Not applicable

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the treatment of a wastewater streamthat is generated from animal processing such as the processing ofchicken, beef or pork. More particularly, the present invention relatesto the enhanced separation of waste solids from an animal processingwastewater stream using a rare earth density modifier (lanthanum,cerium, or praseodymium salts) which causes a modification to theprotein phase density to enhance lipid fat phase separation from proteinsolids. A method and apparatus of the present invention results in areduction in volume of the wastewater solids solution that mustotherwise be trucked away from the processing plant and disposed of.

2. General Background of the Invention

Significant solid waste is generated because of the wastewater treatmentprocess in the food processing industry. Animal by-products that arestrictly considered waste are processed into a wastewater sludge thatmust be removed from the plant and disposed of elsewhere. Most of thiswaste is disposed of by the permitted spread of the sludge over aspecified number of acres, or landfilling of the waste solids. This canbe both time consuming and costly.

Various methods have been used to concentrate and dewater the materialfor disposal. A need exists to enhance the separation of the wastewaterstream in order to reduce the transportation and spreading costs.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved animal processing wastewaterstream treatment that minimizes sludge disposal transportation costs andreduces permitted land application acreage. A method and apparatus ofthe present invention utilizes a rare earth/water mix which is injectedinto the wastewater stream at the plant, resulting in the reduction ofthe waste sludge volume by as much as 50% or more.

With an improved method and apparatus of the present invention, densitymodifiers acting as separation agents can be comprised of rare earthsalts of lanthanum, cerium, praseodymium or a combination thereof. Thedensity modifier used as part of the present invention preventsoxidation of the lipid fraction, serving as an antioxidant of thewastewater stream. This has the dual benefit of stabilizing theoxidation rate of the wastewater fraction (which can be important formeeting city wastewater standards), as well as enabling furtherprocessing of the solid fraction of the wastewater stream.

The present invention provides an improved method of treating awastewater stream from an animal processing facility (e.g., poultry,beef or pork). In one embodiment, the wastewater stream is pumpedthrough a first stage chemical injection stage or location, which can bea section of the wastewater piping system (for example, a flocculationunit or floc tube) located just before entering a first dissolved airfloatation (DAF) unit. Flocculation units are commercially available(e.g., www.frcesystems.com). Dissolved air flotation units arecommercially available (www.frcsystems.com).

First Stage Treatment

The first chemical introduced during the first chemical injection stageis preferably a mineral acid (for example, sulfuric acid (H₂SO₄)) orhydrochloric acid or an organic acid (i.e., carbonic, citric or acetic).First stage injection of chemicals can use a first flocculation unit orfloc tube. In one embodiment, sulfuric acid can be used to adjust the pHvalue of the wastewater stream to between about 6 and 9. The pH valuecan be adjusted to about 4.8-5.2 in another embodiment.

The injection of acid (e.g., sulfuric acid) is preferably followed bythe injection of a density modifier (such as a lanthanum chloride watermix, for example, lanthanum chloride crystal or any compound withlanthanum, cerium, or praseodymium salts). Finally two polymers areadded, one cationic (for example 504650 manufactured by SNF FLOERGER)and one anionic (for example AN945 manufactured by SNF FLOERGER). Thedensity modifier is preferably injected into the wastewater stream at arate of between about 10 and 1000 (milligrams per liter). In oneembodiment the density modifier is injected at a rate of 80-240milligrams per liter.

After the first stage treatment chemical injection is completed, thewastewater stream flows into a first dissolved air floatation (DAF1)unit. Dissolved air flotation units are known and commercially availablesuch as model PCL Series manufactured by FRC SYSTEMS International. Inits modified state (i.e., after first chemical injection stagetreatment), protein floats to the top of the dissolved air flotationunit, separating from the wastewater. The protein can be skimmed into asludge hopper or other suitable vessel and then pumped or otherwisetransmitted to trucks for transport to a suitable disposal locale. Dueto this invention and the new density modifier (e.g., lanthanum, whichis FDA approved), the skimmed material (dissolved air flotation “float”or “skimmings”) includes protein and fat that can be separated and thenused to make animal feed.

In one embodiment, the density modifier can be lanthanum, a lanthanumsalt, a lanthanum water mix, cerium, praseodymium salt or a combinationof one or more of lanthanum, lanthanum salt, lanthanum water mix,cerium, praseodymium salt.

Stage II Treatment

After the protein is skimmed off the top of the first dissolved airflotation unit, the first stage treatment is complete. The nowsignificantly purified wastewater stream is transmitted or pumped into aholding tank with a capacity of between 100,000 and 1,000,000 gallons,for example about 300,000 gallons.

With a wastewater flow rate of, for example, 1,200,000 gallons/day, a300,000 gallon capacity holding tank allows the wastewater to be held inthe holding tank, for example, for between two and five hours.

During this time, the density modifier helps to drive a reaction thatincreases the alkalinity of the wastewater to a pH of between about6.0-6.5, which in turn enhances the further purification of thewastewater stream, and reduces the need for additional treatment with amineral acid, such as sulfuric acid.

From the holding tank (e.g., 300,000 gallon volume), the wastewater istransmitted (e.g., pumped) through the wastewater piping system to thesecond stage chemical injection location (which could be, for example, asecond flocculation unit or floc tube) located just before entering asecond dissolved air flotation unit.

The first chemical introduced during the second chemical injection stagetreatment could be a mineral acid (for example sulfuric acid orhydrochloric acid). Due to the chemical reaction driven by the densitymodifier (or combination of modifiers), the need for sulfuric acid(H₂SO₄) during this section state is much reduced, and is optional ornot required at all.

The injection of the sulfuric acid, if any, is followed by the injectionof the density modifier (for example, lanthanum/water mix), and (as inthe first stage treatment) by the two polymers, one cationic and oneanionic. A flocculation unit can be used.

A rare earth density modifier is injected into the wastewater stream ata rate of between about 10-1000 milligrams/liter in one embodiment, and80-240 milligrams/liter in another embodiment.

After the second stage chemical injection treatment is completed, thewastewater stream flows into a second dissolved air flotation unit(DAF2). In its newly modified state during stage II treatment proteinagain floats to the top of the DAF unit (second dissolved air flotationunit), separating from the wastewater, and is skimmed off the top into asludge hopper or other vessel.

In one embodiment, chemical analyses can be located at the wastewateroutflow locations of both dissolved air flotation units (DAF1 and DAF2),allowing detailed chemical analyses of the wastewater at both locations.The DAF units can be obtained from Vanaire, Inc. (www.vanaire.com).

After discharge from the second dissolved air flotation unit, thewastewater stream is now suitable for discharge into, for example, amunicipal waterstream, and is well within required regulatory parametersfor safety.

The rare earth density modifiers can be lanthanum, cerium, praseodymiumor a combination of one or more of these rare earth density modifiers.In one embodiment a mix of water and one or more of these rare earthdensity modifiers can be used. In one embodiment, an example of1000-liter batch (2204 lb.) includes 441 lbs. LaCl₃ (lanthanum chloridecrystals) and 1,763 lbs. city source H₂O. LaCl₃ equals 45% lanthanumchloride heptahydrate=Cl₃H₁₄LaO. H₂O equals potable water such as citysource. In another embodiment the city source water can be pretreatedwith HCL. ORP (oxidation reduction potential) can be used to vary acidcontent of solution water and for process control to insure consistentquality control. A 10% dilute phase Baume HCL “hydrochloric acid” can beused with ORP tuning in same way. HCL can be used to increase H+ content“cationiticity” and solvent capacity of the makeup water.

An alternate formula makes a 1000-liter batch (2,240 lb.). The alternateformula uses equal amounts of a straight lanthanum blend and aluminumsalt (e.g., 1,102 pounds of each). Aluminum salt equals AluminumChloride, Aluminum Sulfate, Aluminum Chlorohydrate “ACH” or saltsthereof in various commercially available quantities from Gulbrandsen.The aluminum salt product is blended in various concentrations: 20/80;50/50; and 80/20.

In another embodiment, any combination of the above products combinedwith high molecular weight organic copolymers in the family of productsproduced by SNF Floerger to include: Floquat FL 4340, 4420, 4440, 4450,4520, 4530, 4535, 4540, 4620, 4820 which are products in the cationicPolyDADMAC family produced by SNF and Floquat FL 2250, 2273, 2350, 2550,2565, 2650, 2850, 2949, 3050, 3150 which are products in the cationicPolyamine family produced by SNF FLOERGER.

These products are blended in various combinations with the two primaryblends of 1) straight lanthanum or 2) in combination with thelanthanum/aluminum salt blends (e.g., 20/80, 50/50, 80/20). Blends withsodium silicate can be used to increase surface area such as 80/20,50/50, 20/80 blend. Above blends in combination with activated silicacan be used to produce lanthanum silicate.

Blends with the above (e.g., straight lanthanum chloride or lanthanumwith an aluminum salt) in combination with chitosan, a naturallyoccurring biopolymer whereby lanthanum acetate or lanthanum citrate isutilized to put the chitosan solids into solution. Prepare lanthanumacetate by dissolving lanthanum oxide into a solution of acetic acid orconversely lanthanum oxide is dissolved into citric acid to preparelanthanum citrate. The 5-30% stock solution of lanthanum acetate orlanthanum citrate is then used to dissolve commercial grade chitosan,derived from the deacetylation of crustacean based chitin, to produce abiocompatible copolymer for use in animal feed. Chitosan is blended withlanthanum acetate/citrate by dissolving the chitosan in a tank solutionof lanthanum acetate/citrate in 5-30% concentrations to prepare thepolymer solution. The polymer solution is then applied in dosage ratesof 10-1000 mg/l but preferably in the range of 80-240 mg/l using a feedpump.

The present invention includes a method of treating an animal processingwastewater stream, comprising the steps of:

-   -   a) providing a first stage that treats the wastewater stream to        provide a pH range of between about 6 and 9;    -   b) in the first stage, preferably adding cationic and anionic        polymers to the wastewater stream;    -   c) preferably adding a density modifier to the wastewater        stream, the density modifier including lanthanum salt, cerium        salt, or praseodymium salt or a combination thereof at a dosage        rate of between about 10-1000 milligrams per liter; and    -   d) separating density modified material that includes solids        from the wastewater stream with one or more dissolved air        flotation units.

In one or more embodiments, a second stage includes transmitting thewastewater stream to a holding tank.

In one or more embodiments, in step “a” the wastewater stream pH can beadjusted to a value of between about 4.8-5.2.

In one or more embodiments, in step “c” the density modifier can includelanthanum salt.

In one or more embodiments, in step “c” the density modifier can includecerium salt.

In one or more embodiments, in step “c” the density modifier can includepraseodymium salt.

In one or more embodiments, in step “c” the dosage rate can be betweenabout 80-240 milligrams per liter.

In one or more embodiments, the second stage includes holding thewastewater stream in the holding tank for 1-4 hours.

In one or more embodiments, wastewater stream can be held in the tankfor 2-4 hours.

In one or more embodiments, the wastewater stream can be discharged fromthe holding tank to a chemical injection treatment that injects adensity modifier.

The present invention includes a method of treating an animal processingwastewater stream, comprising the steps of:

-   -   a) providing a first stage treatment that treats the wastewater        stream to provide a pH range of between about 6 and 9;    -   b) in the first stage, preferably adding cationic and anionic        polymers to the wastewater stream;    -   c) adding a density modifier to the wastewater stream, the        density modifier including one or more of lanthanum, cerium, or        praseodymium salts at a dosage rate of between about 10-1000        milligrams per liter;    -   d) after step “c” separating density modified material that        includes solids from the wastewater stream with a dissolved air        flotation unit;    -   e) holding a volume of the wastewater stream in a holding tank        for a time period of between 1 and 12 hours;    -   f) discharging the volume of step “e” from the holding tank;    -   g) a second stage treatment including treating the volume        discharged in step “f” with a second density modifier; and    -   h) using a second dissolved air floatation unit to remove        protein from the wastewater stream after step “g”.

In one or more embodiments, the wastewater preferably flows in acontinuous stream between steps “a” and “d”.

In one or more embodiments, the polymers of step “b” are dosed at a rateof between 5 and 50 milligrams per liter of wastewater.

In one or more embodiments, the wastewater in step “a” has an initialbiological oxygen demand (B.O.D.) of between about 1800-3000 milligramsper liter.

In one or more embodiments, the wastewater has a biological oxygendemand (B.O.D.) step “d” of between about 500-1000 milligrams per liter.

The present invention includes a method of treating an animal processingwastewater stream, comprising the steps of:

-   -   a) providing a first stage treatment that treats the wastewater        stream with a floc tube;    -   b) in the first stage preferably adding cationic and anionic        polymers to the wastewater stream;    -   c) adding a density modifier to the wastewater stream, the        density modifier including one or more of lanthanum salt, cerium        salt, or praseodymium salt at a dosage rate of between about        10-1000 milligrams per liter;    -   d) after step “c” separating density modified material that        includes solids from the wastewater stream with a dissolved air        flotation unit;    -   e) holding a volume of the wastewater stream in a holding tank        for a time period of between 1 and 12 hours;    -   f) discharging the volume of step “e” from the holding tank;    -   g) a second stage treatment including treating the volume        discharged in step “f” with a second density modifier; and    -   h) using a second dissolved air floatation unit to remove        protein from the wastewater stream after step “g”.

In one or more embodiments, the material removed can be separated intofat and protein.

In one or more embodiments, the removed material can be dissolved airflotation “float”.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages ofthe present invention, reference should be had to the following detaileddescription, read in conjunction with the following drawings, whereinlike reference numerals denote like elements and wherein:

FIG. 1 is a diagram of a preferred embodiment of the apparatus of thepresent invention and showing the method of the present invention;

FIG. 2 is a diagram of a preferred embodiment of the apparatus of thepresent invention and showing the method of the present inventionshowing the extraction process; and

FIG. 3 is a diagram of a preferred embodiment of the apparatus of thepresent invention and showing a method for mixing lanthanum and water.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a preferred embodiment of the apparatus of the presentinvention designated generally by the numeral 10. Wastewater treatmentsystem 10 can include a first phase to replace ferric salts and toverify treatment efficacy. A second phase verifies yields onprotein/fat. In FIG. 1 , wastewater flow 11 from an animal processingplant can be for example about one thousand gallons per minute (1,000gpm). The raw biological oxygen demand (B.O.D.) of this wastewaterstream 11 can be between about 1800-2000 milligrams per liter (mg/l).The first stage treatment can include a first flocculation unit or floctube 16. A second stage treatment can include a second floc tube 20 aspart of a second chemical injection site. As part of the first stage ofthe method of the present invention, acid 12 (e.g., sulfuric acid,hydrochloric acid) is added to acidify wastewater stream 11, bringing pHto between 4.8 and 5.2, preferably about 5.0. A density modifier 13 isthen added to wastewater stream 11, between 10 and 1000 milligrams perliter (mg/l), preferably between about eighty to two hundred forty(80-240) milligrams per liter. The density modifier 13 can be lanthanum,lanthanum salt, a lanthanum water mix, cerium, praseodymium salt or acombination of one or more of those. Arrows 34, 35, 36, 37 schematicallyillustrate flow of chemicals from vessels 12, 13, 14, 15 to firstflocculation unit 16 via flow lines 22, 23, 24, 25. Each flow line 22,23, 24, 25 can be equipped with a pump (30, 31, 32, 33 in FIG. 1 ) toassist in transmission of material in vessels 12, 13, 14, 15 toflocculation unit 16. A cationic polymer 14 can then be added towastewater stream 11 between and 50 mg/l, preferably about 8 mg/l. Ananionic polymer 15 is added preferably between about 5 and 50 mg/l andpreferably about 8 mg/l. After the chemical treatment in firstflocculation unit 16, the wastewater stream discharges from flocculationunit 16 to first dissolved air floatation unit 17 via flow line 47. Indissolved air floatation unit 17, protein floats to the top of thedissolved air flotation unit 17 where it can be skimmed off into asludge hopper or other suitable vessel.

This treated wastewater stream exits first dissolved air flotation unit17 via line 48 with a pH of between about 4.8 and 5.2, preferably about5.0. This treated waste stream has a B.O.D. of between about 500-1000mg/l. The treated wastewater discharged from first dissolved airfloatation unit 17 is pumped/transmitted via line 48 to a holding tankor reactor vessel 18 (e.g., 300,000 gallons). Treated wastewater isretained in holding tank/reactor 18 for 1 to 12 hours. In reactor vessel18, a lanthanum promoted redox reaction occurs that produces alkalinity.

The reactor 18 effluent is pumped/transmitted via flow line 46 (arrow19) to a second phase chemical treatment which can include use of asecond flocculation unit 20. The flow rate to the second flocculationunit 20 and second dissolved air flotation vessel 21 can be between1,000 and 1,500 gallons per minute, such as about 1200 gallons perminute. In line chemical injection at second flocculation unit or floctube 20 further reduces the B.O.D. of the wastewater stream to less than240 mg/l. Chemical injection of sulfuric acid 12, rare earth/lanthanummix 13, cationic polymer 14 and anionic polymer 15 are via flow lines26, 27, 28, 29 as shown in FIG. 1 . Each flow line 26, 27, 28, 29 can besupplied with a pump (38, 39, 40, 41 in FIG. 1 ). Arrows 42, 43, 44, 45schematically show flow from vessels 12, 13, 14, 15 via flow lines 26,27, 28, 29 to second flocculation unit 20.

Flow line/arrow 22 designates flow of the wastewater stream from secondflocculation unit 20 to second dissolved air floatation unit 21. Proteinfloats to the top of the second dissolved air floatation unit 21separating from the wastewater and is skimmed off the top of thedissolved air floatation unit into a sludge hopper or selected vessel.Recovered skimmed material is now suitable for disposal or furtherprocessing such as separating the fat and protein. After the chemicaltreatment with the selected rare earth density modifier of secondflocculation unit 20 and second dissolved air floatation unit 21treatment, the wastewater stream is suitable for discharge via flow line49 into, for example, a municipal water stream and is well withinrequired regulatory parameters for safety (e.g., BOD equals 500-1,000 mgper liter).

FIG. 2 shows an extraction process of the apparatus and method of thepresent invention. Dissolved air floatation “float” from the processingplant (dissolved air flotation units) is preferably dried in a vacuumrotary dryer (and then preferably baked in an oven, if necessary) untilthe solid content is approximately 85%.

The process of separating the protein meal from the fat is as follows:

The dried dissolved air floatation “float” is placed into an extractionvessel 50, which preferably has a heat resistant liner bag, until thebag is approximately 90% full. The vessel 50 is preferably closed usinga quick-closure lid 60. Extraction vessel 50 can have a volume of 2,100L, a temperature of 60° C., and a pressure of 70 bar, and can hold 550gallons.

At this time, a heated solvent from solvent storage tank 56 and viaheater 53 is pumped with solvent pump 54 and compressor 59 into theextraction vessel 50 (for example, acetone, ethyl, laurate, hexane,and/or CO₂) at a ratio of 10% solvent to 90% dissolved air floatation“float”.

Solvent storage tank 56 can have a volume of 3,000 L and ambienttemperature, and can hold 800 gallons. Solvent heater 53 can be 5 KW.Solvent pump 54 can be 10 KW. Compressor 59 can be 40 KW.

The CO₂ is then pumped from a CO₂ storage 55 into the extraction vessel50 until the desired pressure is attained. For example, for a 2100 liter(≈550 gallons) vessel, and a temperature of 60° C. (140° F.), the CO₂ ispumped via pump 58 into the extraction vessel 50 until a pressure of 70Bar (1000 psi). CO₂ storage 55 can have a volume of 2,000 L, atemperature of 20° C., and a pressure of 60 bar, and can hold 500gallons.

The cycle is repeated at least one more time, or multiple times.

When the desired number of cycles have been completed, the extractionvessel 50 is pressurized using the CO₂, and the new separated fat is“pressed” out of the extraction vessel 50 through a bottom valve 61.

The compound of fat, acetone and some CO₂ now flows through piping 68 toa CO₂ evaporator 57 (150 kilowatt for example) where the CO₂ gas is sentto a CO₂ condenser 52 (150 KW) and then returned in liquid form into theCO₂ storage tank 55. Evaporator 57 can be 150 KW. Condenser can be 150KW.

Meanwhile, the fat/acetone (solvent) compound enters a separator 51 at atemperature of, for example 30° C. (70° F.) and a pressure of 1000 psi.Alternatively, the fat/acetone compound could be processed through adistiller (for example, 100 liter) at a temperature of 150° C. (302° F.)and a pressure of 1 Bar (14 psi).

The acetone is separated in the liquid/gaseous form, and leaves theseparator 51 (or distiller) and enters into the solvent storage tank 56for the next cycle. Separator 51 can have a volume of 100 L, atemperature of 30° C., and a pressure of 70 bar.

The dried protein meal bag is removed from the extraction vessel 50, thefat is removed from the separator 51 (distiller) and the next cyclebegins.

FIG. 3 shows a method of mixing lanthanum and water. Lanthanum is acommercially available solid crystal material. The lanthanum is placedin a hopper 67. Auger or conveyor device 62 transports the lanthanuminto a mixing tank 63. Mixing tank 63 can be about 8′ diameter and about7′ in height, and can hold about 2,000 gallons. Lanthanum is dissolvedwith water in mixing tank 63 with rotating paddles 64. Paddles 64 can bedriven by motor drive 69 and drive shaft 70. The mixture of lanthanumand water is then pumped via piping 65 to holding tank 66. Holdingtank/vessel 66 can be 12′ diameter and 8′ in height, and can hold about7,500 gallons. Holding tank/vessel 66 can be provided with dischargepipe 71.

The following is a list of parts and materials suitable for use in thepresent invention:

PARTS LIST: PART NUMBER DESCRIPTION 10 treatment system 11 wastewaterstream/influent pipe 12 acid/vessel 13 density modifier/vessel 14cationic polymer/vessel 15 anionic polymer/vessel 16 flocculationunit/floc tube 17 first dissolved air flotation unit 18 reactor/vessel19 arrow - reactor discharge 20 flocculation unit/floc tube 21 seconddissolved air flotation unit 22 flow line/arrow 23 flow line/arrow 24flow line/arrow 25 flow line/arrow 26 flow line/arrow 27 flow line/arrow28 flow line/arrow 29 flow line/arrow 30 pump 31 pump 32 pump 33 pump 34pump 35 pump 36 pump 37 pump 38 pump 39 pump 40 pump 41 pump 42 arrow 43arrow 44 arrow 45 arrow 46 flow line 47 flow line 48 flow line 49 flowline 50 extraction vessel 51 separator 52 CO₂ condenser 53 solventheater 54 solvent pump 55 CO₂ storage 56 solvent storage 57 CO₂evaporator 58 CO₂ pump 59 compressor 60 quick closure lid 61 valve 62auger/conveyor device 63 mixing tank 64 paddles 65 piping 66 holdingtank 67 hopper 68 piping 69 motor drive 70 drive shaft 71 pipe

All measurements disclosed herein are at standard temperature andpressure, at sea level on Earth, unless indicated otherwise. Allmaterials used or intended to be used in a human being arebiocompatible, unless indicated otherwise.

The foregoing embodiments are presented by way of example only; thescope of the present invention is to be limited only by the followingclaims.

The invention claimed is:
 1. A method of treating an animal processingwastewater stream which includes lipids and protein solids, the methodcomprising: a) providing a first stage that acidifies the wastewaterstream, wherein the wastewater stream pH is adjusted to a value in therange of 4.8-5.2; b) adding a density modifier to the wastewater stream,said density modifier including lanthanum, cerium, or praseodymium saltsor a combination thereof at a dosage rate in the range of 10-1000milligrams per liter; c) adding a cationic polymer to the wastewaterstream; d) adding an anionic polymer to the wastewater stream; and e)separating density modified floating material that includes proteinsolids from the wastewater stream with one or more dissolved airflotation units.
 2. The method of claim 1 wherein a second stageincludes transmitting the wastewater stream to a holding tank.
 3. Themethod of claim 1 wherein in “b” the density modifier includes lanthanumsalt.
 4. The method of claim 1 wherein in “b” the density modifierincludes cerium salt.
 5. The method of claim 1 wherein in “b” thedensity modifier includes praseodymium salt.
 6. The method of claim 1wherein in “b” the dosage rate is between in the range of 80-240milligrams per liter.
 7. The method of claim 2 wherein the second stageincludes holding the wastewater stream in the holding tank for 1-4hours.
 8. The method of claim 7 wherein the wastewater stream is held inthe tank for 2-4 hours.
 9. The method of claim 2 further comprisingdischarging the wastewater stream from the holding tank to a chemicalinjection treatment that injects a further density modifier.
 10. Themethod of claim 1, wherein the material that is separated is furtherseparated into fat and protein.
 11. A method of treating an animalprocessing wastewater stream including lipids and protein solids, themethod comprising: a) acidifying the wastewater stream, wherein thewastewater stream pH is adjusted to a value of in the range of 4.8-5.2;b) adding a first density modifier to the wastewater stream, saiddensity modifier including one or more of lanthanum, cerium, orpraseodymium salts; c) adding a cationic polymer to the wastewaterstream; d) adding an anionic polymer to the wastewater stream; e) after“d” separating density modified floating material that includes proteinsolids from the wastewater stream with a dissolved air flotation unit;f) holding a volume of the wastewater stream in a holding tank for atime period of between 1 and 12 hours; g) discharging the volume of “f”from the holding tank; h) treating the volume discharged in g) with asecond density modifier; and i) using a second dissolved air floatationunit to remove material that includes protein solids from the wastewaterstream after “h”.
 12. The method of claim 11 wherein the first densitymodifier and the second density modifier include lanthanum salt.
 13. Themethod of claim 11 wherein the first density modifier and the seconddensity modifier include cerium salt.
 14. The method of claim 11 whereinthe first density modifier and the second density modifier includepraseodymium salt.
 15. The method of claim 11 wherein in “b” the dosagerate is in the range of 80-240 milligrams per liter.
 16. The method ofclaim 11 wherein the wastewater flows in a continuous stream between “a”and “e”.
 17. The method of claim 11 wherein the polymers of “c” and “d”are dosed at a rate of between 5 and 50 milligrams per liter ofwastewater.
 18. The method of claim 11 wherein the wastewater has aninitial biological oxygen demand (B.O.D.) in the range of 1800-3000milligrams per liter.
 19. The method of claim 11 the wastewater has abiological oxygen demand (B.O.D.) in the range of 500-1000 milligramsper liter after “e”.
 20. The method of claim 11, wherein the materialthat is separated is further separated into fat and protein.
 21. Themethod of claim 20, wherein the material that is separated is dissolvedair flotation “float”.
 22. A method of treating an animal processingwastewater stream including lipids and protein solids, the methodcomprising: acidifying the wastewater stream to a pH value in the rangeof 4.8-5.2; adding a density modifier to the wastewater stream, saiddensity modifier including one or more of lanthanum, cerium, orpraseodymium salts; adding a cationic polymer to the wastewater stream;adding an anionic polymer to the wastewater stream; and separatingdensity modified floating material that includes protein solids from thewastewater stream.
 23. The method of claim 22, wherein the material thatis separated is further separated into fat and protein.
 24. The methodof claim 23, wherein the material that is separated is dissolved airflotation “float”.
 25. The method of claim 22, wherein the material thatis separated is dissolved air flotation “float”.